docs: def build_hypo_depth_dist(hdd):
      """
      Returns the hypocentral depth distribution as a Node instance
  
      :param hdd:
          Hypocentral depth distribution as an instance of :class:
          `openquake.hzardlib.pmf.PMF`
      :returns:
          Instance of :class:`openquake.baselib.node.Node`
      """
      hdds = []
      for (prob, depth) in hdd.data:
          hdds.append(
              Node("hypoDepth", {"depth": depth, "probability": prob}))
      return Node("hypoDepthDist", nodes=hdds)